1. Field of the Invention
The present invention relates to a subject information processing apparatus that uses a photoacoustic tomography and an ultrasonic wave echo.
2. Description of the Related Art
From the past, there has been known a photoacoustic effect in which if an electromagnetic wave is irradiated onto a biological object, a photoacoustic wave is generated from the biological object due to a temperature increase and thermal expansion of body tissues of the biological object that are attributable to electromagnetic wave absorption. The photoacoustic wave is a typical ultrasonic wave, but in the following description, an ultrasonic wave generated due to the photoacoustic effect is referred to, particularly, as a photoacoustic wave or a photoacoustic signal. Meanwhile, an ultrasonic wave generated by an ultrasonic wave echo is referred to simply as an ultrasonic wave or an ultrasonic signal for discrimination. A technique called a photoacoustic tomography (PAT) has recently been spotlighted which makes the inside of the biological object visible in a noninvasive manner. There is also an attempt to apply this technique to clinical practice. Further, it is expected that a degree of accuracy of diagnosis will be greatly improved in clinical practice by combining a photoacoustic image obtained in real time with an ultrasonic image obtained by a general ultrasonic wave echo technique.
In a photoacoustic tomography device, light is irradiated onto a target subject, and a photoacoustic wave generated thereby is received by a probe that includes a one-dimensional or two-dimensional receiving element array in which a plurality of receiving elements are disposed. As the receiving element array, one similar to a probe typically used in an ultrasonic wave echo device is widely used. Further, in image reconstruction of the photoacoustic tomography, an attempt to apply various algorithms has been made, but a technique called phasing addition generally used in image data generation of the ultrasonic wave echo device can also be applied. Therefore, an attempt to combine the photoacoustic tomography device with the ultrasonic wave echo device, share a signal processor and an image processor, and form both a photoacoustic image and an ultrasonic image has been made (see Japanese Patent Application Laid-Open (JP-A) No. 2005-21380).